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Merge pull request #1043 from jpoimboe/double-constprop

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create-diff-object: simplify mangled function correlation
This commit is contained in:
Joe Lawrence 2019-10-07 13:46:17 -04:00 committed by GitHub
commit df5730076f
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 14 additions and 82 deletions
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94
kpatch-build/create-diff-object.c
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@ -297,6 +297,13 @@ static int is_special_static(struct symbol *sym)
*/
static int kpatch_mangled_strcmp(char *s1, char *s2)
{
/*
* ELF string sections aren't mangled, though they look that way. Just
* compare them normally.
*/
if (strstr(s1, ".str1."))
return strcmp(s1, s2);
while (*s1 == *s2) {
if (!*s1)
return 0;
@ -389,11 +396,7 @@ static int rela_equal(struct rela *rela1, struct rela *rela2)
if (rela_toc1->addend != rela_toc2->addend)
return 0;
if (is_special_static(rela_toc1->sym))
return !kpatch_mangled_strcmp(rela_toc1->sym->name,
rela_toc2->sym->name);
return !strcmp(rela_toc1->sym->name, rela_toc2->sym->name);
return !kpatch_mangled_strcmp(rela_toc1->sym->name, rela_toc2->sym->name);
}
static void kpatch_compare_correlated_rela_section(struct section *sec)
@ -443,7 +446,7 @@ static void kpatch_compare_correlated_section(struct section *sec)
sec1->sh.sh_entsize != sec2->sh.sh_entsize ||
(sec1->sh.sh_addralign != sec2->sh.sh_addralign &&
!is_text_section(sec1)))
DIFF_FATAL("%s section header details differ", sec1->name);
DIFF_FATAL("%s section header details differ from %s", sec1->name, sec2->name);
/* Short circuit for mcount sections, we rebuild regardless */
if (!strcmp(sec->name, ".rela__mcount_loc") ||
@ -763,7 +766,8 @@ static void kpatch_correlate_sections(struct list_head *seclist1, struct list_he
list_for_each_entry(sec1, seclist1, list) {
list_for_each_entry(sec2, seclist2, list) {
if (strcmp(sec1->name, sec2->name))
if (kpatch_mangled_strcmp(sec1->name, sec2->name) ||
sec2->twin)
continue;
if (is_special_static(is_rela_section(sec1) ?
@ -797,8 +801,8 @@ static void kpatch_correlate_symbols(struct list_head *symlist1, struct list_hea
list_for_each_entry(sym1, symlist1, list) {
list_for_each_entry(sym2, symlist2, list) {
if (strcmp(sym1->name, sym2->name) ||
sym1->type != sym2->type)
if (kpatch_mangled_strcmp(sym1->name, sym2->name) ||
sym1->type != sym2->type || sym2->twin)
continue;
if (is_special_static(sym1))
@ -894,77 +898,6 @@ static void kpatch_mark_grouped_sections(struct kpatch_elf *kelf)
}
}
/*
* When gcc makes compiler optimizations which affect a function's calling
* interface, it mangles the function's name. For example, sysctl_print_dir is
* renamed to sysctl_print_dir.isra.2. The problem is that the trailing number
* is chosen arbitrarily, and the patched version of the function may end up
* with a different trailing number. Rename any mangled patched functions to
* match their base counterparts.
*/
static void kpatch_rename_mangled_functions(struct kpatch_elf *base,
struct kpatch_elf *patched)
{
struct symbol *sym, *basesym;
char name[256], *origname;
struct section *sec, *basesec;
int found;
list_for_each_entry(sym, &patched->symbols, list) {
if (sym->type != STT_FUNC)
continue;
if (!strstr(sym->name, ".isra.") &&
!strstr(sym->name, ".constprop.") &&
!strstr(sym->name, ".cold.") &&
!strstr(sym->name, ".part."))
continue;
found = 0;
list_for_each_entry(basesym, &base->symbols, list) {
if (!kpatch_mangled_strcmp(basesym->name, sym->name)) {
found = 1;
break;
}
}
if (!found)
continue;
if (!strcmp(sym->name, basesym->name))
continue;
log_debug("renaming %s to %s\n", sym->name, basesym->name);
origname = sym->name;
sym->name = strdup(basesym->name);
if (sym != sym->sec->sym)
continue;
sym->sec->name = strdup(basesym->sec->name);
if (sym->sec->rela)
sym->sec->rela->name = strdup(basesym->sec->rela->name);
/*
* When function foo.isra.1 has a switch statement, it might
* have a corresponding bundled .rodata.foo.isra.1 section (in
* addition to .text.foo.isra.1 which we renamed above).
*/
sprintf(name, ".rodata.%s", origname);
sec = find_section_by_name(&patched->sections, name);
if (!sec)
continue;
sprintf(name, ".rodata.%s", basesym->name);
basesec = find_section_by_name(&base->sections, name);
if (!basesec)
continue;
sec->name = strdup(basesec->name);
sec->secsym->name = sec->name;
if (sec->rela)
sec->rela->name = strdup(basesec->rela->name);
}
}
static char *kpatch_section_function_name(struct section *sec)
{
if (is_rela_section(sec))
@ -3429,7 +3362,6 @@ int main(int argc, char *argv[])
kpatch_mark_grouped_sections(kelf_patched);
kpatch_replace_sections_syms(kelf_base);
kpatch_replace_sections_syms(kelf_patched);
kpatch_rename_mangled_functions(kelf_base, kelf_patched);
kpatch_correlate_elfs(kelf_base, kelf_patched);
kpatch_correlate_static_local_variables(kelf_base, kelf_patched);

2
test/unit/objs

@ -1 +1 @@
Subproject commit 510a90ca8d35c09574d449ea0f171a7a9baaf087
Subproject commit a5fd47f575552ef989b6b14de84460de5ce0b4ea